High accuracy Location Estimation of a Mobile Tag using One-way UWB Signalling

This paper presents a novel algorithm for determining
the 3D location of a Mobile Tag (MT) using wireless Base
Stations (BSs) and Ultra Wide Band (UWB) one-way signaling.
The algorithm is designed for low power, rapid deployment
applications in which the BSs are independent, wireless UWB
transceivers located at known positions and the tags are receiveonly
or transmit-only UWB mobile units. The algorithm utilizes
multi-BS time synchronization and hybrid Time Difference of
Arrival-Time of Flight (TDoA-ToF) localization to achieve high
accuracy tag localization. The algorithm consists of two concurrent
tasks. In task I, the BSs exploit periodic inter-BS transmissions
to obtain high accuracy multi-BS time synchronization.
In task II, a hybrid TDOA-TOF algorithm is used to determine
the location of the MT. The algorithm is based on timestamping,
or control, of packet Time of Emission (ToE) and estimation
of the packet Time of Arrival (ToA). As such, the method is
appropriate for use with, but not limited to, IEEE 802.15.4a
UWB. In simulations assuming a typical 2 cm standard deviation
in ToA estimation error the proposed algorithm was found to
provide a RMS error of 2.1 ps and 4.8 ∗ 10−6 ppm for time offset
and crystal clock offset between BSs respectively; and a RMS
error in MT location estimation of 2.2 cm; which is 36% better
accuracy than the conventional TDoA method.